Alloys of the CuAlS2 – CuFeS2 system were prepared by thermobaric treatment at high pressure of 5.5 GPa and temperatures ranging from 573 to 1573 K and phase formation in the system was investigated using X-ray powder diffraction, optical microscopy and scanning electron microscopy equipped with energy dispersive spectroscopy. The unit-cell parameters (the lattice constants and the unit-cell volume) were computed as a function of the composition. Absence of complete solubility in the (CuAlS2)1-x-(CuFeS2)x system was established. Formation of solid solutions with the tetragonal structure of chalcopyrite was detected for compositions with the molar part of CuFeS2 x not exceeding 0.10.

Hydrogenated microcrystalline Silicon-Germanium (μc-SiGe:H) thin films were deposited using the Plasma Enhanced Chemical Vapor Deposition (PECVD) technique from a gas mixture of SiH4, GeH4, H2 and Ar at a substrate temperature of 200 ° C. The films were deposited at a pressure of 1.5 Torr, while the RF power was varied in the range of 20 W to 35 W. Structural, optical and electrical characterization was performed in the films, Fourier Transform Infrared Spectroscopy (FTIR) was performed in order to analyze the hydrogen bonding of silicon and germanium, while Raman spectroscopy was used in order to analyze the crystallinity of the films. Through the optical and electrical characterization of the films, parameters such as the optical band gap (Eg) and the activation energy (EA) were obtained, respectively. The conductivity of the films changed up two to orders of magnitude from dark conditions to illumination AM 1.5. Finally, the correlation between deposition RF power and the film properties is presented.

An as-deposited film with a Cr compositional gradient (22–15 at.% Cr) was immersed in 22.5% HNO3 for 15 hours. In the part of the film with initial Cr content in the range of 22–18 at.%, Cu dealloying resulted in sufficient Cu dealloying (final Cr content = 33–80 at.%) without film dissolution. Using the film with optimal initial composition Cu82Cr18, we successfully fabricated a nanoporous film with a pore size in the range of 20–40 nm. As a result of the formation of Cr2O3 during dealloying, this film was transparent and exhibited an insulation state. The novel nanoporous film is expected to be applied as a nanofilter in moisture-in-oil sensors.

Compact-size kilohertz (kHz) AC-supercapacitors are being pursued for ripple current filtering and pulsed energy storage. However, their development is limited by a small areal capacitance density due to very thin electrode used for meeting frequency requirement. In our work, crosslinked carbon nanofiber aerogel (CCNFA) was investigated as freestanding electrode for kHz AC-supercapacitors with an areal capacitance density as large as 4.5 mF cm-2 at 120 Hz, 5-10 times larger than most reports. The CCNFA was obtained in a rapid plasma carbonization process of bacterial cellulose. The fabrication route adopted here is simple and straightforward, and the produced CCNFA electrode was found to be very suitable for high-frequency AC-supercapacitors. The operating voltage range of CCNFA based AC-supercapacitors can be expanded to 3 V by utilizing an organic electrolyte. In addition to AC-Supercapacitor performance, the morphology and material properties of bacterial cellulose aerogel and CCNFA were also reported.

Ternary lead chalcogenides, such as PbSxSe1-x, offer the possibility of room-temperature infrared detection with engineered cut-off wavelengths within the important 3-5 micron mid-wave infrared (MWIR) wavelength range. We present growth and characterization of aqueous spray-deposited thin films of PbSSe. Complexing agents in the aqueous medium suppress unwanted homogeneous reactions so that growth occurs only by the heterogeneous reaction on the hydrophilic substrate. The strongly-adherent films are smooth with a mirror-like finish. The films comprise densely packed grains with tens of nm dimensions and a total film thickness of ∼400-500 nm. Measured optical constants reveal absorption out to at least 4.5 μm wavelength and a ∼0.3 eV bandgap intermediate between those of PbS and PbSe. The semiconducting films are p-type with resistivity ∼1 and 85 Ohm-cm at 300 and 80 K, respectively. Sharp x-ray diffraction peaks identify the films as Clausthalite-Galena solid-state solution with a lattice constant that indicates an even mixture of PbS and PbSe. The photoconductive response is observed at both nitrogen and room temperature up to at least 2 kHz chopping frequency.

A novel synthesis of Al (1xxx)/carbonised coconut shell (CCS) nanoparticles using a ball milling technique was investigated. Initial Al/0.1%CCS powders of an average size of 51.06μm was milled for a period of 70 h. The milled particles at 16, 46 and 70 h were characterized using X-ray diffractomer (XRD), scanning electron microscope (SEM), transmission electron microscope and UV-Vis spectrophotometer. Result revealed that the calculated particle crystallite size from XRD aided with Scherrer’s equation is consistent with particle image sizes obtained from SEM aided with software. TEM image depicted variation in orientation and appearance of the Al 1xxx/0.1% CCS nanoparticles at different milling time. The wide variation in the particle size is attributable to different ball impacts on the individual powders during the ball milling process. Increased maximum absorbance observed with the milled particles when compared with the initial powders is an indication of quantum/nanosizing effect due to ball milling.

When nanoparticles and nanofibers combined at the nanoscale, they could create new features in the material and therefore new areas of use. In this study, polyvinylpyrrolidone (PVP) nanofibers containing carbon nanoparticles produced by dense medium plasma technology have been fabricated via electrospinning technique for the first time, a new class of nanocomposite mat material has been prepared and evaluated for medical devices. A dense medium plasma technique is used for nanoparticles synthesis, which is novel, cost-efficient, and fast technology when is compared with other common nanoparticles synthesis techniques. Carbon based nanoparticles are synthesized from an arc sustained in benzene (purity, 99.5%) between iron electrodes by the lab-made dense medium plasma system. The study first mentions the production of nanoparticles by a pressure of 8 bar argon gas for glow discharge in a period of 9 seconds using a 0.5 cm electrode distance in a liquid environment (volume of benzene: 30 ml). Then, separated carbon nanoparticles are integrated with the PVP nanofibers produced by the electrospinning method. Processing parameters of PVP nanofibers containing carbon nanoparticle (nanocomposites) are optimized with various conditions such as polymer concentration: 7.8-8.0 %w/v, ratio of nanoparticle to polymer solution: 1-3.9 mg /ml, distance of electrode: 10-25 cm, processing time: 5-30 min. All samples are characterized by contact angle measurements, scanning electron microscopy and transmission electron microscopy. At the same time, electrical conductivity of nanocomposite mats are tested for foreseeing usage in biomedical application. Results showed that carbon nanoparticles have diameters in 25 ± 5.4 nm. New nanocomposite material production is proven by transmission electron microscopy. It is a super hydrophilic mat material (static contact angle is lower than 10°). According to the optimization of processing parameters, the diameters of nanocomposite fibers reach down to 150 ±75 nm., Nanocomposite mat resistance is found to be dramatically higher than that for the bare PVP nanofiber mat resistance. According to these results, usage in biomedical application of new material was discussed. It has a great potential to use as biocompatible, light, insulator new material.

The chemical-vapor deposition conditions for the growth of pure boron (PureB) layers on silicon at temperatures as low as 400°C were investigated with the purpose of optimizing photodiodes fabricated with PureB anodes for minimal B-layer thickness, low dark current and chemical robustness. The B-deposition is performed in a commercially-available Si epitaxial reactor from a diborane precursor. In-situ methods commonly used to improve the cleanliness of the Si surface before deposition are tested for a deposition temperature of 450°C and PureB layer thickness of 3 nm. Specifically, high-temperature baking in hydrogen, and exposure to HCl are tested. Both material analysis and electrical diode characterization indicate that these extra cleaning steps degrade the properties of the PureB layer and the fabricated diodes.

The crystallization of (9-X) K2O-1Li2O-12MgO-10B2O3-40SiO2-16Al2O3-12MgF2-X PbO/BaO/ZnO (X =0/5) composition (wt.%) were studied by means of dilatometry, DSC, XRD, SEM and microhardness analysis. Density of base K-Li-Mg-B-Si-Al-F glass (2.59 g.cm–3) is found to be increased on addition of the network modifier oxides PbO, BaO and ZnO content. Addition of Pb2+, Ba2+ and Zn2+ furthermore increased the glass transition temperature (Tg.). A characteristic exothermic hump is found to be appeared in DSC thermograph at the temperature range 800-950°C; and that is ascribed to the formation of crystalline phase fluorophlogopite mica, KMg3(AlSi3O10)F2. Opaque glass-ceramics were prepared from K-Li-Mg-B-Si-Al-F glasses (with and without containing PbO, BaO and ZnO content) by controlled heat-treatment at 1000°C. Interlocked type microstructure combined of flake like fluorophlogopite mica crystals is obtained in ZnO-containing K-Li-Mg-B-Si-Al-F glass-ceramic; and such microstructural pattern is ascribed to cause large thermal-expansion (>11.5×10-6/K, 50-800°C).Vickers Microhardness of base glass-ceramic (5.12 GPa) is increased when contains ZnO (5.26 GPa). ZnO-containing boroaluminosilicate glass-ceramic is, hence, considered with potential interest as they can exhibit the microcrack resistivity in high temperature recycling operation (like SOFC).

Issues on tin (Sn) doping in the mist chemical vapor deposition of α-Ga2O3 was attributed to conversion of ionization states of Sn from Sn4+ to Sn2+ and/or out-diffusion of Sn after thermal annealing, resulting in highly resistive films. Silicon (Si) doping, instead, was succeeded by the use of a novel doping source of chloro-(3-cyanopropyl)-dimethylsilane [ClSi(CH3)2((CH2)2CN)]. Si was uniformly incorporated in the α-Ga2O3 films and the electrical properties were stable even after the thermal annealing. The activation ratio as donors was nearly 100%. The carrier (electron) concentration was controlled to the level of 1018 cm-3 by the [Si]/[Ga] ratio in the source solution. The maximum mobility was 31.5 cm2/V⋅s, in contrast to 24 cm2/V⋅s with Sn doping, suggesting advantage of Si doping . However, the reduction in dislocation defects in the α-Ga2O3 films formed owing to heteroepitaxy on sapphire was suggested to be the important subject to be considered in the next stage.

Imaging of nanoscale structures buried in a covering material is an extremely challenging task, but is also considered extremely important in a wide variety of fields. From fundamental research into the way living cells are built up to process control in semiconductor manufacturing would all benefit from the capability to image nanoscale structures through arbitrary covering layers. Combining Atomic Force Microscopy (AFM) with ultrasound has been shown a promising technology to enable such imaging in various configurations. Here we report the development of an alternative method of combining AFM with ultrasound which we call SubSurface Ultrasonic Resonance Force Microscopy (SSURFM) and which is based on a combination of the two most common variants described in literature, which each have their specific strong points: Ultrasonic Force Microscopy (UFM) and Contact Resonance AFM (CR-AFM). We show the excellent performance of this combination on a number of samples designed specifically to mimic relevant conditions for the application as a metrology technique in the semiconductor manufacturing process. We also discuss the physics of the image contrast mechanism which is based on sensing local changes in visco-elastic properties of the sample bygenerating large indentations in the surface.

Polymer-non-leaded metal (tin, bismuth-tin (BiSn) alloy, and tungsten) composites were prepared to investigate the effectiveness of their X-ray shielding. Films of the composites were found to exhibit excellent X-ray shielding due to the uniform dispersion of metal particles in the polymer matrix, as were fabrics impregnated with the BiSn alloy. The fabricated composites effectively absorb penetrating photons. The preparation of composites with a uniform dispersion and a multilayered structure can limit the formation of pin holes. Multilayered BiSn composites exhibit significantly enhanced shielding. The lamination of a tungsten composite film or a BiSn composite film onto a BiSn-coated layered sheet results in better and more uniform shielding. Thus non-leaded BiSn metal-polymer composites can be used in X-ray shielding applications instead of the lead. One advantage that metal BiSn has over tungsten is its low melting temperature, which means that it can be processed in a normal extruder or in internal mixers such as those used in polymer processing.

To free ourselves from the use of fossil fuels that are highly polluting, life-threatening and not easily regenerated, new technologies are being developed to obtain alternative energy sources more efficiently. Among these technologies, there is the option to improve the performance of solid oxide fuel cells (SOFCs) to make them highly energy efficient. Solid oxide fuel cells (SOFCs) have attracted much attention because they are environmentally benign, sustainable, generate low emissions and have relative low cost. However, conventional SOFCs with yttria-stabilized zirconia (YSZ) electrolyte require high operating temperatures (800-1000°C), which often lead to material degradation problems. Given that the greatest disadvantage of SOFCs is their high operating temperature, samples of CeO2 were synthesized by spray pyrolysis method and doped with Sm2O3 and Eu2O3 to improve the ionic conductivity of the electrolyte so that it can operate at lower temperatures without losing its efficiency. The samples were analyzed using SEM, EDS, TEM. Further research will be made by small angle DRX, AFM, EIS and a prototype will be built to test the working temperature of the electrolyte.

Alpha-alumina is a ceramic with excellent chemical stability, mechanical property, high melting point, and insulating property; however, it shows poor workability due to its low fracture toughness. There are a lot of molding processes for α-alumina, such as press molding and extrusion methods. 3D printing is rapidly growing technology to make complex and precious moldings. However, there are still only a few descriptions on 3D ink-jet powder laminating printings for α-alumina due to no self-hydration hardening property. To achieve α-alumina moldings with the 3D ink-jet printers, powder fluidity of α-alumina powders and binders for bonding the powders should be investigated. The powders mixed with α-alumina at 20, 3.4 and 0.4 μm in sizes were adjusted to improve powder fluidity and packing density. Polyvinyl alcohol (PVA) or polyallylamine (PAA) including other additives was used as an ink. The addition of PVA on the adjusted powders made no chemical interaction of powders and no retention of shapes, but that of PAA formed the printed moldings. The relative packing density and compressive strength of the printed moldings were 40 % and 8.2 kPa, which was clearly depended on the printed directions due to the nozzle structure of printer head. Sintering the moldings at 1500°C caused near-net zero shrinkage and improved the maximum compressive strength at 3.6 MPa.

Microwave synthesis of Copper Zinc Tin Sulphide (CZTS) sphere like particles has been demonstrated. The structural and morphological properties of CZTS particles are characterized by XRD, SEM and Raman spectroscopy and subsequently thermoelectric properties are investigated. XRD results of prepared powder sample matches well with tetragonal crystal structure of CZTS bulk. No other impurity phase has been detected from the XRD analysis. Raman spectrum further confirms the formation of single phase CZTS with characteristics peak for CZTS at 334.1 cm-1. SEM studies reveal that the CZTS particles are spherical in shape with uniform sizes of ∼ 250-350 nm. Hot pressed CZTS system shows a power factor ∼21 µW/mK2 and ZT∼ 0.024 at 623 K. Significant enhancement in the Figure of merit for CZTS system is observed in comparison to reported nanostructures of the same system may be due to increased electrical conductivity.

The proximity of minerals found in human hard tissues may influence cell phenotype. Since cells respond to a range of environmental cues, this study sought to identify the influence of two apatite-based microparticles, hydroxyapatite (HA) and fluoroapatite (FA), upon dental and bone cells. After bone marrow stromal cells (BMSCs), 7F2 osteoblasts and dental pulp stem cells (DPSCs) were plated into media with or without HA or FA particles, the cells were analyzed for alkaline phosphatase (ALP) production, collagen I production, osteocalcin production, and mineralization for two weeks. The BMSCs and DPSCs in media without any microparticles produced more ALP compared to those with microparticles from Day 5 forward. In addition, the collagen I and osteocalcin production in cultures without microparticles was higher than in cultures containing either HA or FA particles. While some studies have shown increased osteogeonic differentiation in the presence of mineral particles, those studies used nanoparticles that were able to be internalized by the cells and were smaller than the microparticles used in this study.